// JavaScript Document
/**
*@description : 图片滤镜工具类
*@date : 2013-10-29
*@author : copy from internet
*@class : gfilter
*/
var gfilter = {
    type: "canvas",
    name: "gfilter",
	version : 'v-1.0',
    /**
     * invert color value of pixel, new pixel = RGB(255-r, 255-g, 255 - b)
     * 
     * @param binaryData - canvas's imagedata.data
     * @param l - length of data (width * height of image data)
     */
 	colorInvertProcess: function(binaryData, l) {
		for (var i = 0; i < l; i += 4) {
	        var r = binaryData[i];
	        var g = binaryData[i + 1];
	        var b = binaryData[i + 2];
	
	        binaryData[i] = 255-r;
	        binaryData[i + 1] = 255-g;
	        binaryData[i + 2] = 255-b;
	    }
 	},
 	
 	/**
 	 * adjust color values and make it more darker and gray...
 	 * 
 	 * @param binaryData
 	 * @param l
 	 */
	colorAdjustProcess: function(binaryData, l) {
		for (var i = 0; i < l; i += 4) {
	        var r = binaryData[i];
	        var g = binaryData[i + 1];
	        var b = binaryData[i + 2];

	        binaryData[i] = (r * 0.272) + (g * 0.534) + (b * 0.131);
	        binaryData[i + 1] = (r * 0.349) + (g * 0.686) + (b * 0.168);
	        binaryData[i + 2] = (r * 0.393) + (g * 0.769) + (b * 0.189);
	    }
	},
 	
	/**
	 * deep clone image data of canvas
	 * 
	 * @param context
	 * @param src
	 * @returns
	 */
	copyImageData: function(context, src)
	{
	    var dst = context.createImageData(src.width, src.height);
	    dst.data.set(src.data);
	    return dst;
	},
	
	/**
	 * convolution - keneral size 5*5 - blur effect filter(Ä£ºýÐ§¹û)
	 * 
	 * @param context
	 * @param canvasData
	 */
	blurProcess: function(context, canvasData) {
		console.log("Canvas Filter - blur process");
		var tempCanvasData = this.copyImageData(context, canvasData);
		var sumred = 0.0, sumgreen = 0.0, sumblue = 0.0;
		for ( var x = 0; x < tempCanvasData.width; x++) {    
            for ( var y = 0; y < tempCanvasData.height; y++) {    
    
                // Index of the pixel in the array    
                var idx = (x + y * tempCanvasData.width) * 4;       
                for(var subCol=-2; subCol<=2; subCol++) {
                	var colOff = subCol + x;
                	if(colOff <0 || colOff >= tempCanvasData.width) {
                		colOff = 0;
                	}
                	for(var subRow=-2; subRow<=2; subRow++) {
                		var rowOff = subRow + y;
                		if(rowOff < 0 || rowOff >= tempCanvasData.height) {
                			rowOff = 0;
                		}
                		var idx2 = (colOff + rowOff * tempCanvasData.width) * 4;    
    	                var r = tempCanvasData.data[idx2 + 0];    
    	                var g = tempCanvasData.data[idx2 + 1];    
    	                var b = tempCanvasData.data[idx2 + 2];
    	                sumred += r;
    	                sumgreen += g;
    	                sumblue += b;
                	}
                }
                
                // calculate new RGB value
                var nr = (sumred / 25.0);
                var ng = (sumgreen / 25.0);
                var nb = (sumblue / 25.0);
                
                // clear previous for next pixel point
                sumred = 0.0;
                sumgreen = 0.0;
                sumblue = 0.0;
                
                // assign new pixel value    
                canvasData.data[idx + 0] = nr; // Red channel    
                canvasData.data[idx + 1] = ng; // Green channel    
                canvasData.data[idx + 2] = nb; // Blue channel    
                canvasData.data[idx + 3] = 255; // Alpha channel    
            }
		}
	},
	
	/**
	 * after pixel value - before pixel value + 128
	 * ¸¡µñÐ§¹û
	 */
	reliefProcess: function(context, canvasData) {
		console.log("Canvas Filter - relief process");
		var tempCanvasData = this.copyImageData(context, canvasData);
		for ( var x = 1; x < tempCanvasData.width-1; x++) 
		{    
            for ( var y = 1; y < tempCanvasData.height-1; y++)
            {    
    
                // Index of the pixel in the array    
                var idx = (x + y * tempCanvasData.width) * 4;       
				var bidx = ((x-1) + y * tempCanvasData.width) * 4;
				var aidx = ((x+1) + y * tempCanvasData.width) * 4;
                
                // calculate new RGB value
                var nr = tempCanvasData.data[aidx + 0] - tempCanvasData.data[bidx + 0] + 128;
                var ng = tempCanvasData.data[aidx + 1] - tempCanvasData.data[bidx + 1] + 128;
                var nb = tempCanvasData.data[aidx + 2] - tempCanvasData.data[bidx + 2] + 128;
                nr = (nr < 0) ? 0 : ((nr >255) ? 255 : nr);
                ng = (ng < 0) ? 0 : ((ng >255) ? 255 : ng);
                nb = (nb < 0) ? 0 : ((nb >255) ? 255 : nb);
                
                // assign new pixel value    
                canvasData.data[idx + 0] = nr; // Red channel    
                canvasData.data[idx + 1] = ng; // Green channel    
                canvasData.data[idx + 2] = nb; // Blue channel    
                canvasData.data[idx + 3] = 255; // Alpha channel    
            }
		}
	},
	
	/**
	 * 	before pixel value - after pixel value + 128
	 *  µñ¿ÌÐ§¹û
	 * 
	 * @param canvasData
	 */
	diaokeProcess: function(context, canvasData) {
		console.log("Canvas Filter - process");
		var tempCanvasData = this.copyImageData(context, canvasData);
		for ( var x = 1; x < tempCanvasData.width-1; x++) 
		{    
            for ( var y = 1; y < tempCanvasData.height-1; y++)
            {    
    
                // Index of the pixel in the array    
                var idx = (x + y * tempCanvasData.width) * 4;       
				var bidx = ((x-1) + y * tempCanvasData.width) * 4;
				var aidx = ((x+1) + y * tempCanvasData.width) * 4;
                
                // calculate new RGB value
                var nr = tempCanvasData.data[bidx + 0] - tempCanvasData.data[aidx + 0] + 128;
                var ng = tempCanvasData.data[bidx + 1] - tempCanvasData.data[aidx + 1] + 128;
                var nb = tempCanvasData.data[bidx + 2] - tempCanvasData.data[aidx + 2] + 128;
                nr = (nr < 0) ? 0 : ((nr >255) ? 255 : nr);
                ng = (ng < 0) ? 0 : ((ng >255) ? 255 : ng);
                nb = (nb < 0) ? 0 : ((nb >255) ? 255 : nb);
                
                // assign new pixel value    
                canvasData.data[idx + 0] = nr; // Red channel    
                canvasData.data[idx + 1] = ng; // Green channel    
                canvasData.data[idx + 2] = nb; // Blue channel    
                canvasData.data[idx + 3] = 255; // Alpha channel    
            }
		}
	},
	
	/**
	 * mirror reflect
	 * 
	 * @param context
	 * @param canvasData
	 */
	mirrorProcess : function(context, canvasData) {
		console.log("Canvas Filter - process");
		var tempCanvasData = this.copyImageData(context, canvasData);
		for ( var x = 0; x < tempCanvasData.width; x++) // column
		{    
            for ( var y = 0; y < tempCanvasData.height; y++) // row
            {    
    
                // Index of the pixel in the array    
                var idx = (x + y * tempCanvasData.width) * 4;       
				var midx = (((tempCanvasData.width -1) - x) + y * tempCanvasData.width) * 4;
                
                // assign new pixel value    
                canvasData.data[midx + 0] = tempCanvasData.data[idx + 0]; // Red channel    
                canvasData.data[midx + 1] = tempCanvasData.data[idx + 1]; ; // Green channel    
                canvasData.data[midx + 2] = tempCanvasData.data[idx + 2]; ; // Blue channel    
                canvasData.data[midx + 3] = 255; // Alpha channel    
            }
		}
	},
};